[Denis DNT]

Every time we got to a dialogue in the Students' Book, my students would shy away from taking up reading roles until I came up with this:
Step one: (Use your two best students)Two students read out the dialogue but not in English. They look at the text in English and rather read in their mother tongue (Korean in my case). It got everyone of them laughing. The weak students now understood the dialogue fully.
Then step two: Sally (one of the characters in the dialogue) speaks only English and Amy speaks only Korean. Use one top student to do Sally and a weak one. The weak one does Amy.

Once you get through step two everyone of them will be yelling out 'me, me, me' to take roles. Keep interchanging roles until all of them have done Sally.